JPS5916856B2 - Manufacturing method of bicycle frame rack - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a frame rack for connecting bicycle frames.

Conventionally, punching or pressing methods have been employed to manufacture this type of frame rack, but at present both methods are performed through three to six steps. An example is shown in FIG. 1. First, from a metal plate, as shown in FIG.
After that, as shown in Figure B, the cylindrical pipe forming part a of the material c is gradually recessed to a predetermined depth, and each branch pipe forming part b is formed by stamping out 3 to 4 steps. Motete 5 Curve into a semicircular shape. Next, the central part of the cylindrical pipe forming part a is curved as shown in Figure C, and then the cylindrical pipe forming part a is formed into a perfect circle shape as shown in Figures D and E, and the branch pipe forming part b,
b are brought into contact with each other, and the opposing parts of the cylindrical pipe forming part a and branch pipe forming parts b and b are welded with argon to manufacture a frame rack having a branch pipe e on one side of the cylindrical pipe d. I have to. Therefore, with this manufacturing method, many work steps were required to obtain a frame rack, and finishing after welding was troublesome and labor-intensive, resulting in high costs and problems such as the inability to mass-produce at the same time. .

In addition to the manufacturing method described above, there is also a method in which branch pipes are formed by punching a metal material into a predetermined shape, and the cylindrical pipe forming portion of the material is formed into a curve to obtain a frame 20. However, this method requires 3 to 4 steps just to form the branch pipe, and many steps are required to obtain the rack.Moreover, the elongation rate of the material is limited, so the branch pipe is Not only is the length limited, but material breakage 25 occurs during manufacturing, resulting in a high defective rate, resulting in high costs, and it is not suitable for mass production.

In addition, especially in recent years, as bicycles have become more sophisticated, curved patterns have been added to the frame racks, but this type of rack is extremely difficult to manufacture and has become very expensive.

The present invention has been made to solve the above-mentioned problems, and is an attempt to manufacture a frame rack that is extremely simple to manufacture, can be mass-produced, and at a low cost.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

First, a metal pipe material 1 as shown in FIG. 2A is bulged, and the outer peripheral wall of the pipe material 1 is inclined at a predetermined inclination angle with respect to its axis as shown in FIG. B. The bottomed cylindrical tubes 2, 2 are formed symmetrically. This pulging process is performed by inserting the pipe material 1 into a mold and pressurizing fluid etc. from both sides of the pipe material 1 using a known processing method. Thereafter, the protruding tip portions 3, 3 of each cylindrical tube 2 are cut and removed from the position indicated by the dashed dotted line A in FIG. Then, as shown by the opening curve in Figure C, the center portions of the tubes 2, 2 are press punched into a roughly weight shape so that they are left and right symmetrical, and at the same time, the left and right portions of the pipe material 1 are stamped as shown by curves C and C. It is also punched out.

At this time, it is also possible to perform cutting instead of press punching. Then, as shown in FIG. 3, a part of the lower outer periphery of the cylindrical tube 2 is cut off, and the cut edge is formed into a curved line 4, and a roughly V-shaped cut curve 5 is formed on the outer periphery of the cylindrical tube 2.
Two frame racks 7 are formed at the same time, in which branch pipes 6 having a diameter are integrally tilted.

In the above, a part of the cylindrical pipe 2 and the branch pipe 6 are provided with a curved pattern, but in the present invention, it is not necessarily necessary to provide these patterns, and the cylindrical pipe part is obliquely cut with a straight line. It may be unadorned.

Further, the present invention uses a long pipe material, and forms a plurality of sets of cylindrical tubes 2, 2 as shown in FIG. 2B on this vibrator material,
This pipe material may be divided in the same manner as described above to simultaneously form a large number of frame racks. As explained above, the manufacturing method of the present invention requires fewer work steps than the conventional method, and does not require a welding process, so manufacturing is extremely simple and has a low defect rate, and at least two frames can be manufactured in one operation. It has the advantage that racks can be manufactured at the same time.

Furthermore, according to the present invention, all processes can be mechanized and mass production can be carried out. Further, the present invention has the advantage that frame racks with long and short patterns or various curved patterns can be obtained very easily.

Furthermore, in the manufacturing method of the present invention, each part of the frame rack is integrally formed, so that a frame rack with excellent strength can be obtained.

[Brief explanation of the drawing]

Figure 1 shows the conventional frame rack manufacturing process, Figure 2
The figure shows the manufacturing process of the present invention, and FIG. 3 is a perspective view of a frame rack obtained according to the present invention. 1 is a pipe material, 2 is a cylindrical pipe, 3 is a protruding tip, 4 and 5 are decorative patterns, 6 is a branch pipe, and 7 is a frame rack.

Claims (1)

[Claims] 1. A method for manufacturing a bicycle frame rack in which a branch tube is integrally protruded from one side of a cylindrical tube, the method comprising: using a single pipe material and processing the pipe material into a bulge. , a set of two bottomed cylindrical pipes that are mutually symmetrical on the outer circumferential wall of the pipe material, and at least one of them is
The projecting tip of each cylindrical pipe is cut and removed, and then the pipe material is symmetrically divided at its cylindrical body portion to obtain at least two frame racks at the same time. A method for manufacturing a bicycle frame rack. 2. When dividing the pipe material into symmetrical shapes, the cylindrical part and the branch pipes extending on both sides of the part are press punched or cut into curved shapes to form decorative patterns on the cylindrical part and the branch pipes. A method for manufacturing a bicycle frame rack according to claim 1, characterized in that: